[Gmsh] Preservation of physical surface labels after boolean operation

[Christophe Geuzaine]

Hi Andrew,

It's not yet implemented, but it's clearly on our TODO list. (Currently we already preserve the tags of the highest-dimensional entities whenever possible: cf. demos/boolean/fragments_numbering.geo.)

Christophe

> On 15 Apr 2017, at 19:39, andrew <armitatz at gmail.com> wrote:
> 
> 
> Hi,
> 
> The new gmsh 3 is great with the Boolean additions!.
> 
> I would like to ask if there is a way to preserve the labeling of the physical surfaces of the objects and the tool objects before the Boolean operation and pass them to the new objects after the Boolean operation.
> 
> For example in the following geo file there is a main object (b1[]) from extrusion and 3 tool objects (b2[],b3[],b4[]) created from extrusion.
> 
> From these objects I define two physical surfaces (b1[2]=out - plane 5 /b2[3]=inside - plane 11). If I perform a Boolean operation with them I lose the out/inside names and since the numbering of the surfaces changes from the creation of new objects I can't find the inside/out labels any more. Is there a way to preserve the names from the old objects and pass them to the new object? For example the newly created surfaces (plane 40 - plane 25) in the new object that were part of the out surface before could be preserved.
> 
> Something like: Physical Surface("new_out")=FromOld("out") that could assing to the surfaces 40 & 25 the tag 'out' from the surface 5 since these two were created from the breaking of surface 5.
> 
> kind regards
> 
> Andrew Tsiantis
> 
> 
> 
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-- 
Prof. Christophe Geuzaine
University of Liege, Electrical Engineering and Computer Science 
http://www.montefiore.ulg.ac.be/~geuzaine

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